Currently, there is substantial research activity directed toward the discovery and optimization of reactions and reactions products for a wide range of applications. Although the chemistry of many reactions has been extensively studied, few general principles have emerged that allow one to predict with certainty a composition or structure of a material that will exhibit a desired characteristic or to predict reaction pathways that will result in a desired synthesis of a desired material. As such, there exists a need in the art for a more efficient, economical and systematic techniques and apparatus for the synthesis of materials and for the screening of such materials and for screening reactions that form such materials.
Combinatorial material science refers generally to methods for synthesizing a collection of chemically diverse materials and to methods for rapidly testing or screening this collection of materials for desirable performance compositions, characteristics, properties or the like. Combinatorial materials science approaches have greatly improved the efficiency of discovery of useful materials. For example, material scientists have developed and applied combinatorial chemistry approaches to discover a variety of novel materials, including for example, high temperature superconductors, magnetoresistors, phosphors and catalysts. See, for example, with respect to inorganic materials such as heterogeneous catalysts, U.S. Pat. Nos. 6,004,617, 5,985,356, 6,326,090 and 6,410,331 to Schultz et al. See also U.S. Pat. No. 6,514,764 to Willson. In comparison to traditional materials science research, combinatorial materials research can effectively evaluate much larger numbers of diverse compounds in a much shorter period of time. Although such high-throughput synthesis and screening methodologies are conceptually promising, substantial technical challenges exist for application thereof to specific research and commercial goals.
Of particular interest to the present invention are combinatorial methods and apparatuses for screening of materials, including especially screening of catalysts for catalytic activity and/or selectivity. The art includes several approaches that are effective for screening catalysts, including for example, parallel thermal imaging (see, e.g., U.S. Pat. No. 6,333,196 to Willson), parallel sorbent trapping (see, e.g., U.S. Pat. No. 6,410,332 to Schultz et al. and PCT Application No. WO 00/51720 of Bergh et al.), and analysis by parallel gas-chromatography following reaction in a parallel fixed bed reactor (see, e.g., U.S. Pat. No. 6,149,882 to Guan et al., and U.S. Published Application No. 2002-0048536 of Bergh et al.). Although such approaches are effective, it is desirable to develop other, complementary analytical techniques for evaluating materials such as catalysts, and in particular, for evaluating catalytic activity and selectivity. Spectroscopic techniques, such as infrared spectroscopy (e.g., Fourier-transform infrared spectroscopy—FTIR spectroscopy) are of particular interest in view of their universal application for detecting chemical species that are present as reaction products or unreacted reactants of a chemical reaction. Other techniques, such as non-dispersive infrared (NDIR) techniques are also of particular interest for some applications.
Several approaches are known in the art for screening combinatorial libraries of materials such as catalysts, by characterization of reaction products or unreacted reactants using infrared spectroscopy. As one example, U.S. Pat. No. 6,541,271 to McFarland et al. discloses a methodology for characterizing samples on a common substrate preferably using infrared imaging techniques, including infrared spectroscopic techniques such as FTIR spectroscopy. As another example, U.S. Pat. No. 6,623,970 (and corresponding European Patent No. EP 0883806) to Willson discloses general methods and reactor apparatus for evaluating diverse catalysts by detecting reaction products or unreacted reactants using spectroscopy, including infrared spectroscopic techniques such as FTIR spectroscopy. As a further example, International Publication Number WO 01/06209 to Lauterbach et al. is directed toward the creation of Fourier Transforms by operating a spectrometer in either a step scan or rapid scan mode. However, additional challenges remain for more effectively applying infrared spectroscopy to the analysis of materials such as reaction products or unreacted reactants resulting from parallel combinatorial reactions, such as catalyzed reactions. In particular, some of the present approaches are limited with respect to sensitivity for measuring small amounts of reaction constituents. Also, some of the approaches are limited with respect to their ability to be effectively integrated with highly parallel reaction systems, such as massively parallel microreactors.